The Sun Kept Shining
I feel like this story is pretty well-known at this point, but in case you don’t know, Danny DeVito essentially saved It’s Always Sunny in Philadelphia.
Six episodes into the series’ first season, things weren’t going super well. While the show had some fans, the ratings were low, and critics (at the time) weren’t enthusiastic about it. However, it just so happened that DeVito’s children were big fans from the start, and got their father on board with loving the show.
It also happened that DeVito personally knew the head of the FX network, so he arranged a meeting between himself and Rob McElhenney to ask what he could do to help. This conversation eventually led to DeVito’s role as Frank Reynolds, which arguably gave the show way more notoriety and helped propel it into a 14 season run with a 15th season on the way.